JPS60229325A - Method of producing electrolytic condenser - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of manufacturing an electrolytic capacitor.

(Prior Art) Conventionally, anode body materials for electrolytic capacitors include tantalum, nioff, zirconium, and vanadium.

So-called valve action metals such as hafnium, titanium, and aluminum are known, and in the past many researchers have investigated the basic characteristics of these metals alone or in their alloys as electrolytic capacitors, and have considered their practical application. Ta.

However, in order to be put to practical use as a capacitor, the leakage current of the oxide film unique to the anode material is required.

Electrical properties such as dielectric loss must reach a certain level, and the electrolytic capacitors currently in practical use are
Only tantalum and aluminum anode bodies are used.

Capacitors using tantalum as anode material have excellent electrical properties such as leakage current and dielectric loss, are stable and extremely reliable, and are characterized by being compact and having large capacity.

However, the supply of tantalum has not been able to keep up with the increase in demand over the past few years, and due to resource shortages, the price of the material has skyrocketed significantly, leading to an increase in product prices. on the other hand,
Capacitors using aluminum as the anode material have the advantage of being inexpensive, but in addition to being more difficult to miniaturize and increase capacity, they are inferior to capacitors using tantalum as the anode material in terms of electrical characteristics and stability. ing.

Under these circumstances, electrolytic capacitors whose anodes are made of materials that have excellent electrical characteristics such as leakage current and dielectric loss and stability, can be made smaller and larger in capacity, and can be inexpensively and stably supplied are being developed. Development was strongly desired.

As a result of various studies, the present inventors used titanium hydride and aluminum powder as raw materials, mixed, pressed, and sintered these powders to create an aluminum-titanium alloy porous sintered body as an anode body. In some cases, we have discovered that it is possible to obtain a porous material for electrolytic capacitors that meets these needs, and we have already proposed it.

We have also already proposed that when this aluminum-titanium alloy is used as an anode body, the most suitable chemical solution for anodizing is a phosphoric acid aqueous solution.

However, anodic oxidation using this phosphoric acid aqueous solution requires
When MnO is solidified as a typical anode material by thermal decomposition of manganese nitrate, there is a drawback that the capacitance decreases by lθ to 20°. This phenomenon is caused by phosphoric acid A/
- Since it has etching properties for T I alloys, it produces fine irregularities of the order of 10 OA on the surface of the anodic oxide film, resulting in MnO produced by thermal decomposition of manganese nitrate.
This is thought to be due to the fact that the cathode cannot completely cover the film surface, resulting in a so-called non-solidified area. the result.

When a moisture resistance test, which is one of the reliability tests, is performed, a problem arises in that the rate of increase in the capacitance t increases due to the process in which absorbed moisture covers the non-solidified region.

(Objective of the Invention) The object of the present invention is to improve the shortcomings of the anodic oxidation method using a phosphoric acid aqueous solution, such as a decrease in coverage during solidification, and to improve reliability by suppressing an increase in capacity during a humidity test. Excellent Al-
The present invention provides a method for manufacturing a Ti alloy electrolytic capacitor.

(@Ming configuration) According to the present invention, AJI-Ti alloy is used as an anode body.
□ Anodizing the electrolytic capacitor with an aqueous solution containing phosphoric acid and ammonium lactate - thereby obtaining an excellent manufacturing method with less reduction in capacitance during solidification, that is, a greater coverage rate with MnO and the cathode. Can be done.

Hereinafter, the content of the present invention will be explained in detail from Example t.

(Example) Al powder with an average particle size of 3 μm and titanium hydride powder with an average particle size of 3 μm were mixed so that the atomic ratio of M and Ti was 54:46, and the mixture was compression molded into a cylindrical shape.

A u-'ri alloy porous body was produced by holding and sintering at 1070° C. for 2 hours in a vacuum, and used as an anode body. Next, these porous anode bodies were subjected to anodic oxidation using six types of chemical solution concentrations of phosphate-ammonium lactate (samples/161 to 6) as shown in Table 1.

For comparison, anodic oxidation using a phosphoric acid aqueous solution at 80V was also carried out as a conventional method.

(Sample height 7) Next, these samples were impregnated with manganese nitrate solution, the thermal decomposition process was repeated five times, MnO and cathode baking were performed, and then graphite and silver paste were baked, solder dipped, and resin dipped to solidify. did. Table 1 shows the capacitance after solidification (after resin dipping) (120Hz
) Shows the leakage current (16V applied - 5 minute value) and the rate of decrease in temperature during solidification.

In addition, the sample after solidification was tested for humidity resistance (40℃-
The results obtained regarding the increase in capacitance are shown in FIG. 1.

As shown in Table 1, the rate of customer decline during solidification was lower than that of the sample anodized with phosphoric acid-ammonium lactate aqueous solution (7
In the case of 1 to 6), 3.0 to 47% is obtained, which is considerably smaller than the 13% (47) in the case of anodizing with a comparative example phosphoric acid aqueous solution (conventional method). Correspondingly, the increase in capacity in the humidity test shown in Figure 1 is also much smaller in the case of the phosphoric acid-ammonium lactate aqueous solution, and 3~
It can be seen that the increase is only 5%, which is a significant improvement compared to about 14% in the case of the phosphoric acid aqueous solution.

(Effect of the invention) As described above in detail with reference to the embodiments.

According to the manufacturing method of the present invention, IJ −'I' i alloy i
It is possible to significantly reduce the decrease in the number of electrostatic customers when the tm capacitor is solidified, and at the same time, it is possible to reduce the increase in capacity due to moisture resistance and improve the moisture resistance characteristics. Therefore, it is clear that the present invention is highly useful.

[Brief explanation of the drawing]

Figure 1 is a graph showing moisture resistance characteristics. 7″-

Claims (1)

[Claims] A method for manufacturing an electrolytic capacitor, in which an alloy consisting of aluminum and titanium is used as an anode metal, and after anodizing this, a solid cathode semiconductor layer and an external cathode are sequentially formed. A method of manufacturing an electrolytic capacitor, characterized in that the manufacturing method is carried out by: